Welsh and James said the system, which uses elaborate procedures to control the launch of intercontinental ballistic missiles, remains sound.

"Based on everything I know today I have great confidence in the security and the effectiveness of our ICBM force," James said. "This was a failure of some of our airmen. It was not a failure of the nuclear mission."

James said there are checks and balances built into the system that ensure the system would not be compromised.

The cheating ring was uncovered during an investigation into drug use among Air Force officers. That drug probe has implicated 11 officers at six bases.

During the probe, the Air Force Office of Special Investigations uncovered evidence that an officer electronically shared answers to monthly proficiency tests with 16 other officers at the Montana base.

Subsequently, another 17 officers admitted to at least being aware of the information being shared.

The 34 implicated in the scandal have lost their certification and their clearances have been suspended. The Air Force said it is requiring all ballistic missile officers, which number about 600, to retake the proficiency test.